Contact mechanism



Sept; 26, 1944. A. J. MccoNNEL'L Erm. 2,359,136

CONTACT MECHANISM Filed Sept. 23,' 1942 Andrew J. McConnell, William CI.|\'1or-r-s,V

Tlfneilf` Attorney..

' continuity of service.

OONTAUI' c. me he, u n

anarewl.ucoonncu;albm,n.rmawmnm aldgnantaGeneral Bac- New York l Wasserman :arancelaria am aclmwcLm-m) I f Our invention relates to improvements in contact mechanisms for electroresponsive devices and more particularly highly sensitive quickly acting relays. and especially relays which operate in response to predetermined abnormal conditions of an electric circuit.

In order to obtain fast contact controlling action from relays which respond to faults on electric circuits, it is desirable to use small contact gaps. Also, regardless of the magnitude of the energy ordinarily available to effect a circuit a shock resistant backstcp comprising a cushioning member carried by the movable contact of the relay and ensageable with a movable mem- .ber of suiiicient intertia to abmrb shock. Also in accordance with our invention, the movable member is arranged directly to partake of the movement of the movable contact to an amount l dependent on the circuit opening eil'ect of the contact actuating means of the-relay whereby proportionately to increase the contact gap and thus minimise the danger of rebound reclosing clonng operation of the contacts, itis often desirable to use a relatively weak return spring in order to obtain maximum sensitivity of response.

However, these two desirable features, that is,

small gap and weak return spring, result in a hazard if the relay is subjected to shock since the movable contact may readily be shock-actuated to cause a circuit closing operation of the relay contacts. This may be serious, particularly if, as in the case oi' a diil'erentialrelay, there is only one relay controlling the trip circuit of a circuit breaker because the result would ,be an imneecssary interruption in the much desired relays, suchas those which respond to the direction of now of power, there can occur in some cases, such as clearing a fault behind a relay, a sudden change in the direction of the force or torque acting on the movable contact with such\ magnitude-in the circuit opening direction as to cause a quick rebound through the small contact gap to the circuit closing position since the restraint against movementfin this direction is small. As before, this might result in an unnecessary and undesirable circuit breaker tripping operation even though the relay may be cooperating with some other fault responsive relay, such as an instantaneous overcurrent relay whose contacts are in series with the contacts of a power directional relay. y

An oblect of our invention is to provide an improved contact mechanism for electroresponsive devices, relays and the like, such that the advantages accruing from small contact gaps and weak return springs may be retained without danger of false operation because of shock and rebound. Another object of our invention is, in eifect, momentarily so to increase the contact gap when the relay operating i'orceor `torque is strong in the circuit opening direction as to requirea closing time greater than the normal closing time. These and other obiects of our inventionwill hereinafter appear in greater detail.

Furthermore, in certain as well as requiring a greater circuit closing time under certain desired conditions. v

Our invention will be better understood from the following description when considered in connection with the accompanying sheet of drawings, and its scope will be pointed out in the appended claims.

In the accompanying sheet of drawings, Fig. 1 l

is a front elevation of a relay having a contact mechanism embodying my invention; Fig. 2 is a top plan view of the relay. and contact mechanisxn shown in Fig. 1: Fig. -il is a vertical sectionalfview on the line 3-3 oi' Fig. 2; and Fig. 4

is a vertical sectional view, similar to Fig. 3, -illustrating a modiiication of our invention.

'For the purpose of illustrating our invention, we have shown an embodiment thereof as applied to a relay l of the induction cylinder. type such as disclosed, for example. in United States Letters ,Patent Reissue 21,813, issued May 27, 1941.

While our invention is particularly well adapted to a quickly acting high torque relay device, such as disclosed in said Letters Patent, it is to be distinctly imderstood that its application is general and not limited to the specific structure herein with suitable energiiringi windings.

tuating means or motor structure is mounted between suitable ncnmagnetic end frames 8 and il;V preferably having high heat dissipatlng properties. Above the upper end frame 8 is a supporting structure or contact head Il which is of suitable insulating material and which carries a suitably adjustable bearing ii for the .upper end offth'e shaft l. Mounted on this shaft so as to turn 1n accordance with our invention. vwe provide 55 therewith is a movable'contact carrying member ,the contact head I0.

I2 to which is secured a suitable electric current conducting strip I3 provided with a contact I4. The member I2, referring to Fig. 2, is biasedV for counterclockwise movement by a relatively weak spiral spring I5, the inner end I6 of which is in conductive relation with the strip I3 and the outer end I'I of which is conductively secured toa ring I8 of suitable conducting material.

In order to vary the counterclockwise torque of the spring I and thereby change the sensitivity of the relay, the ring I8 is rotatably positioned in an insulating support I9 mounted on To hold the ring in any desired position, it may be clamped against its support I9, as shown in Fig. 2, by suitable means such as a threaded member 20 which passes through terminal 2I of a lead 22, the support I9, the ring IB and a clamping plate 23 set in a notch on the lower side of the support i9. With this arrangement, it will be observed that the spring I5 also acts as a lead-in conductor between the ring I8 and the contact strip i3. Cooperating with the movable contact lli is a relatively stationary contact 24 which is illustrated as of the anti-rebound type disclosed in United States Letters Patent 2,098,032, issued November 2, 1937. This anti-rebound structure comprises a split nut or support 25 provided with a threaded bushing 26 and a clamping screw 2l, all mounted on the contact head l0 with the threaded opening in the bushing suitably inclined to the base of the contact head il). Screwed into the bushing 26 is a threaded barrel or cylinder 28 within which there is a rollable member or ball which normally rests against a diaphragm at the lower end of the housing. Between the diaphragm and a resilient contact support which carries the contact lli is a spacing ring. The contact support, ring and diaphragm are held in place with the ball in the housing 28 by a collar 22, all asdisclosed in said Letters Patent 2,098,032..

`Since for fast circuit controlling action, a small gap, preferably not exceeding three sixty-fourths of an inch, between the contacts id and 2d is essential and vfor maximum sensitivity of response the counter-clockwise torque or' the spring imust be small; it is apparent that any shock transmittedto the relay could readily eirect an undesirable circuit closing operation of the contacts. This would, if these were the only contacts in the circuit 0f the trip coil of a circuit breaker as in the vcase of a differential relay, cause a false circuit opening operation with a possible interruption in the much desired continuity or service. In order to avoid this undesirable shock closing Contact operation, we provide a shock absorbing means which, as shown more clearly in Fig. 3, comprises suitable cushioning means such as a felt pad mounted on the Contact carrying member i2. As shown, this pad is set in a cup which is secured to a metallic strip similar to the contact strip i3 and similarly mounted on the member ln the path of movement of the pad so as to partake ci movement or" the member i2 is a movable inember such as a ball which is reliable in a suitably mounted guideway such as a cylindrical housing Thishousing is screwed into a split and threaded bushing 2u which is so mounted in a split nut or support 25' as te cause the ball to tend to roll down hill toward the pad St. The bushing 25 and the housingT 28 are held in position by a clamping screw 2l'. The ball 33 is maintained in the housing 23 by a collar Eil' having a suitable opening to allow the desired movement of the pad 3U. With this arrangement, it will be noted that any shock to the relay tending to cause a circuit closing movement of the contact carrying member I2 is ineffective.

embodying our invention are particularly eilective under other conditions tending to cause false operation. Thus, for example, if the relay in case of a fault is subjected to a torque in the contact opening direction, the ball 33 will be moved upwardly in the housing 28 an amount dependent upon the magnitude of the torque within the limit of counterclockwise' motion of the contact carrying member I2. During this movement the ball exerts a substantially constant countereffect which is independent of the amount of the contact separation. This movement of the ball permits a relatively large increase in the gap between the contacts i4 and 24 with a steady follow-up by the ball 33 when the torque is removed by the clearing of a fault through the opening of a circuit breaker near the fault. Thus, for example, in the case of a ground directional relay, when a ground fault in the nontripping direction is cleared, tendency for rebounding action or shockto cause a closing of the contacts I4 and 24 is substantially eliminated.

Also if, in the process of clearing a fault, the opening of the iirst circuit breaker results in a reversal of ilow of ground fault power, this sudden reversal will not quickly eiect the closing of the directional relay contacts because of the contact gap increase during the non-tripping direction of ground fault power flow. This is particularly advantageous when a ground fault power directional relay is arranged Awith its contacts in series with the contacts of an instantaneous overcurrent relay in the circuit of the trip coil of a circuit breaker, as is the u-sual practice in the art of circuit protection. With such an arrangement, there is the possibility that with the reversal or ground fault power ilow the contacts oi the power directional relay may close before the contacts of the overcurrent relay can'open. This would, of course, cause a false tripping of the circuit breaker which is highly undesirable. However, if the power directional relay embodies our invention, then a fault power iiow in the nontripping direction will produce a relatively high countercloclrwise torque to push the ,bally contacts lil and is again materially increased.

From the foregoing, it will be observed that..

the combination of the ball and the cushioning member 3@ eliminates the possibility of contact closure with any shock ordinarily to be ex- In addition to the antishock feature, relays pected. Al|io,witl1acontactopeningtrquer or force exerted by the electromagnetic 4actuating means in a direction to increase the contact gap. the rebound is eliminated without any special features such as slip clutches and the ad- 4 il, is o! particular value in absorbing the upward component or lift on the ball I3 due to shock, our invention may be used without this cushioning means, particularly when the contact gapincre'ase eilect is the principal feature desired. Thus, the embodiment oi our invention shown in Pig. 4 may be employed. In this embodiment, the movable contact carrying member I! is in direct engagement with the ball l! without any intervening cushioning means lil. It will be noted that `in either oi' the modiilcations shown in Figs. 3 or 4 the actuation of the ball Il upwardly in its housing is not accomplished by increasing the bias of or storing energy in a spring, which would. tend to cause rebound. In other words, after the movable contact `carrying member I2 engages the movable member 33,' the countereil'ect of the backstop means opposed to thel circuit opening eiiect oi' the actuating means is substantially constant regardless of the extent of the contact separation.

While we have shown and described our invention in considerable detail, we do not desire to be limited to the exact arrangements shown. but seek to cover in the appended claims all those modifications that i'all within the true spirit and scope oi' our invention.

What we claim as new and desire to secure by Letters Patent oi' the United States is:A

1. In a highly sensitive quickly acting electroresponsivc device wherein actuating means are arranged to eil'ect the circuit closing operation of relatively ilxed and movable cooperating contacts and means is provided for effecting a circuit opening ofthe contacts when the device is substantially deenergized; shock-resistant backstop means for maintaining a relatively small gap between said contacts when the device is substantially deenergized comprising a guideway having one end adjacent the movable contact, a member movable in said guideway and .biased toward said one end thereof, and a cushioning member mounted on the movable contact and engageable with said movable member when the contacts are separated more than a predetermined amount.

2. In a highly sensitive quickly acting electroresponsive device wherein actuating means are arranged. to effect the circuit closing operation of relatively nxed and movable cooperating contacts and a relatively weak means is provided for etrectinga circuit opening operation of the contacts when the device is substantially deenergized; shock-resistant backstop-means for maintaining a relatively small gap between said contacts when'the device is substantially deenergiaed comprising a cylindrical housing having an open end adjacent the'movable contact and inclined downwardly toward said contact. a relatively heavy ball in said housing, and a cushioning member mounted on the movable contact and engageable with said ball when the contacts are separated more than a predetermined amount.

3. In a highly sensitive quickly acting electroresponsive device wherein actuating means are arranged to eilect circuit controlling operations oi relatively fixedv and movable cooperating contacts and a relatively weak resilient means is provided for eecting a circuit opening operation of the contacts when the device is substantially deenergised;` shock-resistant backstop meansl for maintaining a contact gap less than three sixty-fourths of an inch when the device is substantially deenergized comprising a cylindrical housing having an open end adjacent the. movable contact andl inclined downwardly toward said contact, a relatively heavy ball in said cylindrical housing arranged directly to partake of the .movement of the movable contact and movable thereby uphill in the housing an amount dependent upon the` circuit opening eflect of the actuating means proportionally to increase the contact gap, and a cushioning member mounted on the movable contact and engageable with said ball when the contacts are separated more than a predetermined amount.

4. In an electroresponsive device wherein actuating means are arranged to effect the circuit closing operation of relatively ilxed and movable cooperating contacts and a relatively weak means is provided for eilectln'g a circuit opening operation of the contacts when the device is of an inch when the device is substantially deenergized comprising a cylindrical housing inclined downwardly toward the movable contact withI one end adjacent thereto, a ball in said housing, and a felt pad mounted onthe movable contact and engageable with said vball when the contacts are separated more than a predetermined amount.

5. In an electroresponsive device wherein actuating means are arranged to effect the circuit closing and circuit opening operations o! a relatively ilxed contact and a movably supported cooperating contactl and a relatively weak means is provided for effecting a circuit opening operation of the contacts; means for hunting the contact separation under the effect of only said relatively weak means to a value less than three sixty-fourths of an inch arranged to permit an eilfective increase in the separation of the contacts when the actuating means tends to cause a circuit opening operation of the contacts comprising a cylindrical housing inclined downwardopening effect oi' said relatively weak means, said ball being directly engageable by the support of the movable contact when the contacts are separated by'said amonut and movable uphill in the housing an amount dependent on the circuit opening"eiect of the actuating means proportionally to increase the separation of the contacts.

c. In s highly Sensitive quick1y acting electro'- responsive device wherein actuating means areerations of a relatively iixed contact and a mova'bly supported cooperating contact andv y a substantially constant counter eiiect to balance the circuit opening effect of said separate means, said movable member being directly engageable by the support of said movable contact when the contacts are separated more than a predetermined amount. d

7. In a highly sensitive quickly acting electroresponsive device wherein actuating means are arranged to effect circuit vcontrolling operations of a relatively fixed contact and a movably supported cooperating contact and a relatively weak resilient means is provided for effecting a circuit opening operation of the contacts; backstop means for limiting the contact gap to a value less than three sixty-fourths of an inch when the device is substantially deenergized comprising a cylindrical housing having an open end adjacent the movable contact andv inclined downwardly toward said contact, a relatively heavy ball in said cylindrical housing for exerting on the support of said movable contact a substantially constant counter effect to balance the circuit opening effect of said resilient means, said ball being directly engageable by the support of the movable contact for movement uphiilin the housing an amount dependent upon the circuit opening eiect of the `actuating means proportionally to increase the contact gap.

8. In an electroresponsive device wherein actuating means are arranged to eiect circuit controlling operations of a relatively xed contact and a movably supported cooperating contact and a relatively weak means-is provided tending to eiect a circuit opening operation of the contacts; means for limitingl the contact separation under the effect of only said relatively weak means to a value less than three sixty-fourths of an inch arranged to permit an effective in-v crease in the contact gap when the actuating means tends to cause an increase in the separa- .tion of the contacts comprising a cylindrical housing inclined downwardly toward the movable contact with one end adjacent thereto and a ball in said housing for balancing the eiect of. said weak means when the 'contact separation is substantially equal to said value, said ball being directly engageable by the support of said movable contact and movable uphill in the housing an amount dependent upon the magnitude of the circuit opening action of said actuating means.

9. In a highly sensitive `quickly acting electroresponsive device wherein actuating means are arranged to effect the circuit controlling operations Ao1' a relatively ilxed contact and .a movably supported cooperating contact and separate means is provided for eiecting a circuit opening of the contacts when the device is substanl tially deenergized; backstop means for limiting the separation of the contacts to a relatively small value in response to the eiect of only said separate means comprising a guideway having one end adjacent the movable contact, and means for exerting on the support of said movable contact a substantially constant counter effect to balance the circuit opening eiect of said separate means comprising a member movable in said guideway biased toward said one end thereof said member being directly engagea'ble by the support of said movable contact for movement in said guideway against said bias when the contacts are separated more than said value.

ANDREW J.` MCCONNELL. WILLIAM C. MORRIS. 

